Application of integral hydraulic-mechanical jarring technique in horizontal wells

Jarring operations are often deployed to release stuck downhole pipe string. In horizontal wells with significant friction resistances, energy released through elastic deformation of pipe string above the jar may be easily consumed by such friction resistances. Consequently, performances of jarring operations are usually unsatisfactory in horizontal wells. In such circumstances, the integral hydraulic-mechanical jarring technique was developed for horizontal wells. The new system contains dual-stage spring cylinder to enhance resilience of the spring accelerator and deploys multiple spring accelerators in series connection to prolong the working travel. With hydraulic boosters, the integral hydraulic-mechanical jarring string for horizontal wells can be deployed to compensate effects of friction resistance in curved borehole to enhance performances. Laboratory tests show that the integral hydraulic-mechanical jarring string for horizontal wells can satisfy design requirements. In addition, suitable technical parameters for application were clarified in accordance with test data. Field applications show that the newly developed integral hydraulic-mechanical jarring technique has outstanding performances, with hook load reduced by 80%. With high applicability, the technique can effectively reduce requirements for workover devices.